1. Field of the Invention
The instant disclosure relates to a granular bed filtration; in particular, to a granular bed filtration system with gas entrained recycling for a thermal power plant using coal-fired power generation technology.
2. Description of Related Art
Once oil and natural gas are exhausted, coal may be left as one of the main sources of fuel for power plants in the future. Therefore, now is the time to begin researching and developing clean coal technology to enhance conversion efficiency as well as to achieve the objective of energy saving and carbon footprint reduction. Currently, the integrated gasification combined cycle (IGCC) is a coal-fired power generation technology that has developmental and applicable potential. Traditionally, IGCC uses various types of filtration devices to filter out dust that was generated by gasification in order to prevent gas or dust containing sulfur and phosphorus from polluting the environment, and protect downstream power generating equipment. Certainly, in a safe national energy stand point, IGCC has a diversified selection of feedstock (coal, biomass, petroleum coke, asphalt, and other domestic waste resources alike for developmental application) which can effectively minimize dependence on a single energy resource, and enhance energy alternatives as well as safety.
Generally, the raw syngas produced from IGCC contains a large amount of fly ash and pollutants. The high temperature, high pressure granular dust substances (such as fly ash) must be filtered out from the raw syngas in order to prevent the high temperature dust substances from depositing onto the blades of syngas turbines, which could be detrimental to the mechanical properties of the blades. Moreover, normal operation of the dynamic system is ensured and service life of turbines is extended. However, in structural design of the traditional IGCC system, filtering and sieving for granular dust substances are mainly through gravity settling chamber, cyclone collector, wet scrubber, electrostatic precipitator, ceramic filters, filter bag dust collectors, and related equipment. But in order to ensure the normal operation of the aforementioned dust removal or cleaning equipment, the high temperature high pressure raw syngas and the granular dust substances traditionally undergo temperature and pressure reduction, thus, resulting in low power efficiency and recontamination from waste water used for temperature reduction. Certainly, the cost investment of complex equipment used for temperature and pressure reduction is a relatively large obstacle for commercialization.
Therefore, the objective is to filter out the granular dust substances from the high temperature high pressure raw syngas without affecting the normal operations while maintaining cost and filtering efficiency.
To address the above issues, the inventor strives via associated experience and research to present the instant disclosure, which can effectively improve the limitation described above.